Where to Buy

The Micro1v8 is available on Amazon:

Micro1v8 (2-Pack) - USB to 1.8V Serial Adapter with LEDs - FTDI FT230X chip

International buyers: Our inventory is "Fulfilled by Amazon" which means that it's up to Amazon to decide where they ship. Currently, they do offer international shipping on our products to most countries. Thank you!

Comparison to the MicroFTX

The Micro1v8 is very similar to the earlier MicroFTX design:

• Same FT230XQ chip
• Same overall size
• Same I/O voltage ranges

With the following improvements:

• On-board 1.8V regulator and 1.8V default I/O level
• On-board TX and RX LEDs
• Simpler jumper configuration to switch to 3.3V operation
• Access to 5V and 3.3V regardless of selected I/O level

And the following tradeoffs:

• Changed pin layout (although VIO, RX, TX, and GND still match)
• No access to CBUSx pins

Drivers

$ adduser $USER dialout

SUBSYSTEM=="usb", ACTION=="add", \
  ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6015", GROUP="plugdev"

Bitbang GPIO

The FT230X supports bitbang GPIO (general-purpose input/output) modes that allow you to set and read digital pins directly. It’s a great way to let your computer drive a simple binary output, or to read the state of a switch. For full details, see the FT230X website and datasheet. FTDI’s bitbang app note AN232R-01 is also a useful reference.

Two forms of bitbang are supported by the chip. They are enabled with FD_SetBitMode (D2XX) or ftdi_set_bitmode (libftdi):

• BITMODE_BITBANG uses the RX, TX, CTS, and RTS pins and works out of the box
• BITMODE_CBUS uses the CBUSx pins, but needs to be enabled first in the EEPROM

Note that the Micro1v8 does not expose the CBUSx pins, so BITMODE_CBUS would probably only be useful for manual control of the onboard LEDs.

On Linux, libftdi provides an easy way to use bitbang. The python bindings are poor, but it’s straightforward in C. This program will toggle the RX, TX, CTS, and RTS pins every time it’s run:

#include <ftdi.h>
#include <err.h>

int main(int argc, char *argv[])
{
    struct ftdi_context ftdi;
    unsigned char x;

    /* Initialize and find device */
    if (ftdi_init(&ftdi) < 0)
        err(1, "ftdi_init");

    if (ftdi_usb_open(&ftdi, 0x0403, 0x6015) < 0)
        err(2, "can't open device");

    /* Enable bitbang */
    if (ftdi_set_bitmode(&ftdi, 0xff, BITMODE_BITBANG) < 0)
        err(3, "can't enable bitbang mode");

    /* Read state & flip it */
    if (ftdi_read_pins(&ftdi, &x) < 0)
        err(4, "can't read");
    x ^= 0xff;
    if (ftdi_write_data(&ftdi, &x, 1) < 0)
        err(5, "can't write");

    /* Close device */
    ftdi_usb_close(&ftdi);
    ftdi_deinit(&ftdi);

    return 0;
}

To test it out, download this file as ftdi-bitbang.c, compile, and run it:

$ sudo apt-get install libftdi-dev build-essential
$ gcc -o ftdi-bitbang ftdi-bitbang.c -lftdi
$ ./ftdi-bitbang

Non-standard Baudrates

The FT230X supports custom baudrates up to 3Mbaud. If you’re using Python’s pySerial module, custom baudrates should just work like any other baudrate:

#!/usr/bin/python
import serial

ser = serial.Serial(port = "/dev/ttyUSB0", baudrate = 2000000)
ser.write("hello, world")
ser.close()

Here is a low-level example of how to configure custom baudrates in C on a Linux system:

#include <termio.h>
#include <fcntl.h>
#include <err.h>
#include <linux/serial.h>

static int rate_to_constant(int baudrate) {
#define B(x) case x: return B##x
    switch(baudrate) {
        B(50);     B(75);     B(110);    B(134);    B(150);
        B(200);    B(300);    B(600);    B(1200);   B(1800);
        B(2400);   B(4800);   B(9600);   B(19200);  B(38400);
        B(57600);  B(115200); B(230400); B(460800); B(500000); 
        B(576000); B(921600); B(1000000);B(1152000);B(1500000); 
    default: return 0;
    }
#undef B
}    

/* Open serial port in raw mode, with custom baudrate if necessary */
int serial_open(const char *device, int rate)
{
    struct termios options;
    struct serial_struct serinfo;
    int fd;
    int speed = 0;

    /* Open and configure serial port */
    if ((fd = open(device,O_RDWR|O_NOCTTY)) == -1)
        return -1;

    speed = rate_to_constant(rate);

    if (speed == 0) {
        /* Custom divisor */
        serinfo.reserved_char[0] = 0;
        if (ioctl(fd, TIOCGSERIAL, &serinfo) < 0)
            return -1;
        serinfo.flags &= ~ASYNC_SPD_MASK;
        serinfo.flags |= ASYNC_SPD_CUST;
        serinfo.custom_divisor = (serinfo.baud_base + (rate / 2)) / rate;
        if (serinfo.custom_divisor < 1) 
            serinfo.custom_divisor = 1;
        if (ioctl(fd, TIOCSSERIAL, &serinfo) < 0)
            return -1;
        if (ioctl(fd, TIOCGSERIAL, &serinfo) < 0)
            return -1;
        if (serinfo.custom_divisor * rate != serinfo.baud_base) {
            warnx("actual baudrate is %d / %d = %f",
                  serinfo.baud_base, serinfo.custom_divisor,
                  (float)serinfo.baud_base / serinfo.custom_divisor);
        }
    }

    fcntl(fd, F_SETFL, 0);
    tcgetattr(fd, &options);
    cfsetispeed(&options, speed ?: B38400);
    cfsetospeed(&options, speed ?: B38400);
    cfmakeraw(&options);
    options.c_cflag |= (CLOCAL | CREAD);
    options.c_cflag &= ~CRTSCTS;
    if (tcsetattr(fd, TCSANOW, &options) != 0)
        return -1;

    return fd;
}

Download this example: linux-custom-baudrate.c.

EEPROM Customization

The FT230X includes a 2048-byte reprogrammable EEPROM that configures the chip. Features that can be customized in the EEPROM include:

• USB vendor ID, product ID, device strings
• Device serial number
• I/O pin drive strength
• UART signal polarity inversion
• CBUS pin selection, allowing the LEDs on the Micro1v8 to be configured as:
  • TX/RX LED outputs (default)
  • USB sleep status and control
  • Battery charge detection output
  • Bitbang GPIO
  • Off (tristate)

The easiest way to reprogram the EEPROM is using FTDI’s FT_Prog utility for Windows. Version 2.6.6 and later support the FT-X series chips. The user manual has more information.

The open-source libftdi library includes functions to access and change the EEPROM contents, and a standalone utility ftdi_eeprom that uses these functions. However, libftdi’s FT-X support is not necessarily complete and may not yet have been updated to support the FT-X chips. Note that incorrectly changing the EEPROM contents may lead to a chip that is difficult to recover.

Other third-party tools to program the EEPROM exist, like ftx-prog.